🔁 Monad Meta Aggregator Swap API Guide

This guide shows how to fetch a swap quote using the monad meta aggregator API with viem in typescript.

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🌐 endpoint

GET https://alpha.clober.io/api/quote

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📥 query parameters

name	type	description
inputTokenAddress	string	address of the input token (e.g. native ETH is 0x0000000000000000000000000000000000000000)
outputTokenAddress	string	address of the token you want to receive
amountIn	string	amount of input token in wei
slippageLimitPercent	string	slippage limit in percent (e.g. "1" for 1%)
userAddress	string (optinal)	user's wallet address (if userAddress is not provided, the API will not build a transaction)

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📦 example request

GET https://alpha.clober.io/api/quote?inputTokenAddress=0x0000000000000000000000000000000000000000&outputTokenAddress=0xf817257fed379853cDe0fa4F97AB987181B1E5Ea&amountIn=1000000000000000000&slippageLimitPercent=1&userAddress=0x5F79EE8f8fA862E98201120d83c4eC39D9468D49

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🧪 using viem + typescript

import axios from 'axios'
import { createWalletClient, http } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import { monadTestnet } from 'viem/chains'

const account = privateKeyToAccount('0xYOUR_PRIVATE_KEY')
const client = createWalletClient({
    account,
    chain: monadTestnet,
    transport: http(),
})

async function fetchAndExecuteQuote() {
    const inputToken = '0x0000000000000000000000000000000000000000' // native ETH
    const outputToken = '0xf817257fed379853cDe0fa4f97AB987181B1E5Ea'
    const amountIn = '1000000000000000000' // 1 ETH in wei
    const slippage = '1'
    const userAddress = account.address

    try {
        const { data } = await axios.get('https://alpha.clober.io/api/quote', {
            params: {
                inputTokenAddress: inputToken,
                outputTokenAddress: outputToken,
                amountIn,
                slippageLimitPercent: slippage,
                userAddress,
            },
        }) as {
            data: {
                bestQuote: {
                    aggregator: string
                    amountOut: string
                    transaction: {
                        to: `0x${string}`
                        data: `0x${string}`
                        value: string
                        gas: string
                        gasPrice: string
                    }
                }
            }
        }

        const best = data.bestQuote
        console.log('✅ best aggregator:', best.aggregator)
        console.log('🔁 expected amountOut:', best.amountOut)

        const tx = best.transaction

        const hash = await client.sendTransaction({
            to: tx.to as `0x${string}`,
            data: tx.data as `0x${string}`,
            value: BigInt(tx.value),
            gas: BigInt(tx.gas),
            gasPrice: BigInt(tx.gasPrice),
        })

        console.log('🚀 sent tx hash:', hash)
    } catch (err) {
        console.error('❌ error while quoting or sending tx:', err)
    }
}

fetchAndExecuteQuote()

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📘 sample response

this is a sample response from the monad meta aggregator quote api. it includes the best available quote and a list of all quotes from supported aggregators.

{
  "bestQuote": {
    "amountOut": "1528866",
    "aggregator": "Monorail",
    "transaction": {
      "from": "0x5F79EE8f8fA862E98201120d83c4eC39D9468D49",
      "to": "0xfD845859628946B317A78A9250DA251114FbD846",
      "data": "0xb69cbf9f0000...", // encoded calldata
      "value": "1000000000000000000",
      "gas": "940662",
      "gasPrice": "52000000000"
    },
    "executionMilliseconds": 330.06097
  },
  "allQuotes": [
    {
      "amountOut": "1528866",
      "aggregator": "Monorail",
      "transaction": {
        "from": "0x5F79EE8f8fA862E98201120d83c4eC39D9468D49",
        "to": "0xfD845859628946B317A78A9250DA251114FbD846",
        "data": "0xb69cbf9f0000...",
        "value": "1000000000000000000",
        "gas": "940662",
        "gasPrice": "52000000000"
      },
      "executionMilliseconds": 330.06097
    },
    {
      "amountOut": "1522248",
      "aggregator": "OpenOcean",
      "transaction": {
        "from": "...",
        "to": "...",
        "data": "...",
        "value": "1000000000000000000",
        "gas": "872528",
        "gasPrice": "52000000000"
      },
      "executionMilliseconds": 347.45342
    },
    {
      "amountOut": "1521628",
      "aggregator": "Clober",
      "transaction": {
        "from": "...",
        "to": "...",
        "data": "...",
        "value": "1000000000000000000",
        "gas": "693416",
        "gasPrice": "52000000000"
      },
      "executionMilliseconds": 274.84042
    }
  ]
}

• amountOut: expected output token amount after the swap (in smallest unit, e.g. wei)
• aggregator: name of the aggregator/router that provides the quote
• transaction: full transaction object that can be submitted via viem.sendTransaction()
  • from: address that will initiate the transaction (usually user’s wallet address)
  • to: router contract address to be called
  • data: encoded calldata for executing the swap
  • value: amount of ETH to send along with the transaction (if input is native ETH)
  • gas: suggested gas limit for executing the swap
  • gasPrice: suggested gas price in wei
• executionMilliseconds: time taken to compute this quote (used for diagnostics)

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